Homework Help:
How do I represent this relationship

-->meaning that whenver you increase x by 1, x also increases by 1 starting with (0,0)( iguess...).

This is to answer this question:

Carbon nanotubes with indices (n, m) that satisfy n-m=3l, where l is an integer, behave likemetals (copper, silver, aluminum, etc). The rest behave like semiconductors (silicon, germaniumetc). Can you identify at least one group of vectors that would produce metallic carbon nanotubes?Find as many as you can if you are able to.

Ok, but this has nothing to do with the coordinate system. The values (n,m) are supposed to components of vectors that are not plotted on a regular 90 degree coordinate system. I just want to express the trend that (3,0), (4,1), etc such that n-m=3(integer).